E46 Fanatics Forum banner
  • Hey everyone! Enter your ride HERE to be a part of September's Ride of the Month Challenge!
1 - 16 of 16 Posts

·
Registered
Joined
·
21 Posts
Discussion Starter · #1 · (Edited)
Ok so I have those 2 secondary air injection codes (P0491 & P0492)…I’ve been battling this problem for a year now. And the code still won’t go away! I’ve replaced everything down the line that involves it! But now I’m second guessing the two hose Inlets at the side of intake manifold. And would like an opinion first because I’ve taken apart that damn thing 8 dozen times and I’m getting really sick of it. Now the oem diagram shows the hose with non return goes on top and then the hose to the reservoir on the bottom, then I’ve seen a diagram on here that shows the reverse and I went the route of the reverse way? Also does that solenoid thing it connects to have a fuse? Maybe the fuse blew for that. I’m so frustrated.
Motor vehicle Automotive design Font Auto part Automotive lighting
Automotive lighting Light Product Automotive tire Bumper
 

·
Registered
Joined
·
130 Posts
1. Does the check valve open when vacuum is applied to the small tube?
2. If you disconnect the hose from the air pump, do you feel strong air during cold start?
3. How old are your O2 sensors?
 

·
Registered
2001 325i Sedan
Joined
·
837 Posts
Have you made sure the air ports in the head are not clogged?? It is trivia to fully test the air pump, air valve, and vacuum solenoid. Once all those are checked, and you still get the codes, then the air ports in the head are almost certainly plugged with exhaust residue.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #9 ·
The pump, check valve, non return all new and hosing all new. Works. Before cat o2’s are new of this year. Not sure the age of after cats. How would I look into this blockage?!? Would taking off the part where the spark plugs are help? Because I need to change the gaskets in there anyways.
 

·
Registered
2001 325i Sedan
Joined
·
837 Posts
The secondary air ports are drilled into the head, and connect the port at the SAP valve to ports directly above all six exhaust ports. I'd be surprised if they can be cleared without removing the head, and rodding out all the drillings. But I would think you should be able to get some idea of their state by blowing air into the SAP valve port, and listening for air flowing into the headers.
 

·
Registered
Joined
·
130 Posts
The secondary air ports are drilled into the head, and connect the port at the SAP valve to ports directly above all six exhaust ports. I'd be surprised if they can be cleared without removing the head, and rodding out all the drillings. But I would think you should be able to get some idea of their state by blowing air into the SAP valve port, and listening for air flowing into the headers.
Can't clean the port out with a long flexible brush?
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #12 ·
The secondary air ports are drilled into the head, and connect the port at the SAP valve to ports directly above all six exhaust ports. I'd be surprised if they can be cleared without removing the head, and rodding out all the drillings. But I would think you should be able to get some idea of their state by blowing air into the SAP valve port, and listening for air flowing into the headers.
Ok great thanks for the info, I will look into the headers this week and report back with my findings lol I’m so sick of this already
 

·
Registered
E30M3 Race F10 535 R1150Rt M Coupe
Joined
·
7,468 Posts
If you have a higher level scan tool? Verify something first.

Use a vacuum pump (if earlier vacuum controlled) to open up the valve on the head. Go into activation's and with the engine OFF, command the secondary pump ON. Get a cigarette or cigar and hold it just inside the tailpipes. Air pressure should push the smoke out.

Go from there.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #14 ·
Exhaust is coming out of the car. I had a problem earlier that there would be like a build up and if I gunned it there would be a ton of exhaust billowing out?
 

·
Registered
E30M3 Race F10 535 R1150Rt M Coupe
Joined
·
7,468 Posts
NOT EXHAUST.

There's conjecture that the passageways for the secondary air ports are clogged.

What I suggested above, will let you know if the air being delivered by the pump is GETTING in/OUT.
All done with the engine OFF.
 

·
Registered
2000 E46 323i, 3.0L and 2.0L Z3's
Joined
·
1,131 Posts
Just skimmed through this thread.

If you have replaced the rubber vacuum lines at the back of the inlet manifold, did you install the 1 way valve (black and white round thing) the correct way around?

Yes, you can blow through and suck on it to see if it is working or not, but you have to remember that you are working with vacuum and not air pressure when you refit it. The air flow is from the SAP back into the manifold (vacuum source).
 
1 - 16 of 16 Posts
Top